It is thought the heart-in-a-box, which is being tested at sites around the world, could save up to 30% more lives by increasing the number of available organs.

The breakthrough has been welcomed around the world.

The British Heart Foundation described it as a 'significant development'.

Maureen Talbot, a senior cardiac nurse at the charity, told the BBC: 'It is wonderful to see these people recovering so well from heart transplantation when, without this development, they may still be waiting for a donor heart.'

Liver warming

Similar methods of warming and nourishing organs before transplant have been used to improve the quality of lung and liver transplants.

James Neuberger, the associate medical director at the UK's NHS Blood and Transplant service, said: 'Machine perfusion is an opportunity to improve the number and quality of organs available for transplant.

'We look forward to more work being carried out to determine the impact of this technology on increasing the number of organs that can safely be used for transplant and on improving the quality of those organs.

'It is too early to predict how many lives could be saved through transplantation each year if this technology were to be adopted as standard transplant practice in the future.'